The legendary naturalist Gerald Durrell once noted that “so-called human progress proceeds at the speed of an Exocet missile, whereas conservation proceeds at the pace of a donkey and cart”. Yet, according to his widow Lee, there could never be any question of giving up – and the phrase “lost cause” was a “red rag to a bull”. Nowhere is this philosophy more apparent than in his unpublished writing, pulled together by Lee Durrell in a new book to mark the centenary of his birth next year.

Drawing on an unfinished memoir – as well as the bones of an unpublished account of his 1969 trip to Australia’s Great Barrier Reef, Northern Territory and Queensland – Myself & Other Animals (Gerry came up with the title himself before his death) celebrates his extraordinary life in technicolour.

Lee says: “There’s a piece I reread when considering whether to include it in the book. It’s called The Magical Creek Lands and comes from his book about his first trip to South America, to British Guiana.

“I found it mesmerising, vintage Durrell. He describes the beauty and tranquility of the remote reaches of the Essequibo River and then tells how he watched a young cayman on the hunt and a mother jacana protecting her brood. It is, perhaps, a bit anthropomorphic, but that is how Gerry plunges you into the drama of the natural world, from which you emerge sensitised to and appreciative of it.

“We need more of this today if our beautiful planet is to be saved.”

While the author and conservationist died in 1995 aged 70, his best-known work, My Family and Other Animals – an account of his somewhat eccentric upbringing on the island of Corfu – remains evergreen, not least thanks to the hit ITV series The Durrells.

Known to friends and family as Gerry, his writing retains the ability to bring the glorious world of nature to life on the page to this day – enrapturing generations and appealing to readers of all ages, backgrounds and inclinations. “He was a natural writer, but he didn’t believe it,” says Lee, 75, of her late husband.

“He felt he had some sort of muse on his shoulder who told him what to write. He would get up at dawn to start writing – by hand – and then finish for the day at about nine or ten, when he would tend to the ‘business’ of Jersey Zoo.

“Gerry often said his brother Lawrence was ‘the real writer’ and that he wrote only to be able to support his conservation mission. He was very humble about his writing, always asking Jacquie, his first wife, and later me, to read what he had written that day, and then he would watch us closely to see our reaction.

“The new book is a new look at Gerald Durrell as a writer and conservationist, as well as a ‘personality’, because it pulls together through his own words the beauty of his prose, the passion of his convictions and his background story, including some stressful experiences as a child and young man.

“I’m sure that as he grew older he became more and more aware of his influence – after all, he received an OBE for his work and his writing – but he never took it for granted.”

Despite such modesty, Durrell’s reputation as a pioneering conservationist has not diminished since his relatively early death as a result of liver cancer. No less a figure than Sir David Attenborough hails his influence as “magic”, while Princess Anne describes him as a “remarkable man” in her introduction to the new book, praising Durrell for “taking effective action to make the world a better place for all living beings and the wild places they inhabit”.

“So many people in the conservation world today tell me that they are in it because of Gerald, his writings and the example he set with his own zoo,” Lee smiles.

“When Gerry was thinking of setting up a zoo for conservation purposes, he sought the opinions of many biologists. Most thought it was a good idea, but said he was mad even to attempt it, including David [Attenborough].

“Being the stubborn man he was, Gerry went ahead with his plans and the Jersey Zoo was born in 1959, fairly quickly earning the respect of the sceptics. Since that time we’ve been pioneers in the role that zoos can and should play in conservation.”

Today called the Durrell Wildlife Conservation Trust, it remains a beacon of good practice, training and supporting conservationists from all over the world.

Lee strongly believes “good zoos” have a vital role to play, despite changing public attitudes towards keeping wild animals in captivity.

“Not only do zoos have a place in conservation and education, but they are vital components of both,” she insists. “Good zoos operate impactful conservation programmes in the field and conduct breeding, research and training programmes for threatened species in the zoo itself.

“Some years ago, it was estimated that 600 million people visited zoos annually, and I imagine there are even more visitors today. The opportunity to engross people in the world of animals and nature is massive in the setting of a good zoo.

“Only with strong feelings of being connected to nature will people change their behaviour for the welfare of the planet. Note that I am saying ‘good zoos’. There are some pretty terrible zoos still around, and Gerry would have been the first to call for their closure. But without good zoos, the world would be a much poorer place.”

Lee met Gerry as a student, before becoming his second wife in 1979.

“I was writing up my PhD dissertation in zoology when Gerry visited my university, Duke University in the US,” she recalls. “I had spent two years with the forest animals of Madagascar doing my field research, which is where I had first read Gerry’s books – by the light of a paraffin lamp – and was enchanted by the books and the author.

“My professors invited me to dinner with the great man, no doubt showing me off as the exotic graduate student who’d worked in a remote corner of the world. When Gerry walked into the room it was as if a thousand-watt light was switched on, so strong was his charisma. You don’t often meet your heroes, much less marry one.”

The pair enjoyed an “amazing life” together, travelling the world to visit the trust’s conservation programmes or to make TV documentaries about threatened species and habitats, while collaborating on books.

Her late husband also loved to cook, having been taught by his mother, especially enjoying preparing Indian-inspired meals for family and friends.

“He also wanted me to become directly involved in the conservation work of the Trust and so asked me to start a recovery project for the most endangered tortoise in the world, the ploughshare tortoise of Madagascar,” continues Lee.

“We have had great success with breeding and release into the wild for this species, as well as with raising conservation awareness in the local communities, so much so that they set up a national park which encompasses the last stronghold of the tortoise.”

Gerald Durrell was born in India in 1925, moving to England with his family following the death of his engineer father Lawrence in 1928.

In 1935, then aged 10, the family – Gerry, his dog, Roger, and his older siblings Lawrence, Margaret and Leslie – moved to Corfu led by redoubtable matriarch Louisa, played on screen in The Durrells by Keeley Hawes. They remained there happily for four years until the outbreak of the Second World War forced them to return to Britain.

While Gerry’s older brother was feted as a literary novelist and poet during his lifetime, it is his own work, humorously chronicling their lives, that has endured and grown in popularity.

Durrell’s lightly fictionalised 1956 memoir, My Family And Other Animals, and its sequels, Birds, Beasts And Relatives, and The Garden Of The Gods, have never been out of print.

“As with most ‘animal people’, Gerry was probably born with an innate love of creatures. It was evident from his days as a toddler in India,” says Lee. “Before he was two, he would insist on going to the local zoo twice a day, his first word being not ‘mama’ or ‘dada’, but ‘zoo’, and he would watch small creatures, like slugs, with endless fascination.

“He adored his kindergarten teacher in Bournemouth, Miss Squigg, as she indulged his love of animals and natural history.

“But arriving in Corfu at the age of 10 was momentous – he described it as Dorothy stepping out of her black and white world in Kansas into the colourful land of Oz.

“He was surrounded by nature and mentored by one of the island’s great naturalists, Dr Theodore Stephanides.

“I think that most children have an affinity with nature, but, sadly, they seem to grow out of it. Gerry never did.”

Even today, Durrell’s work remains enormously influential, and not just through the ITV drama (although Lee retains a huge affection for it and the actor Milo Parker, who played her husband as the boy with an insatiable curiosity for nature).

“It was great television and gave a lot of people a lot of pleasure, as well as introducing, or re-introducing, them to Gerry – and while the story line did not slavishly follow the books word for word, I always say that neither did Gerry himself stick to the absolute truth,” she chuckles. “I visited the set in Corfu a couple of times and Milo was always terrific. We have become friends and he is now an ambassador for Durrell Wildlife Conservation Trust.”

While interest in conservation has soared, support for nature sadly hasn’t kept up in her estimation.

“There has been an enormous change in the understanding of conservation issues over the last 60 years – biodiversity is almost a household word,” Lee says.

“And there is an ever-increasing amount of public support for it, but, sadly, not enough. Other forces today still overwhelm advances in conservation. Gerry once said that so-called human progress proceeds at the speed of an Exocet missile whereas conservation proceeds at the pace of a donkey and cart. Popularity doesn’t necessarily mean action in support of nature, however, but at least it’s a start.”

Was Durrell optimistic for the future, I wonder?

“He always answered that if he didn’t have any hope for the planet, you would find him living in a tropical island paradise revelling in a hedonistic lifestyle,” Lee adds.

“As it was, he never gave up on what many people called ‘lost causes’ – that phrase for Gerry was like a red rag to a bull. A case in point was the situation with the Mauritius kestrel, which had dwindled to only four individuals back in the 1970s.

“Most conservationists had given up on it, but not Gerry and his team. Thanks to them, the species recovered and there are now hundreds of kestrels flying free in Mauritius.”

Myself & Other Animals by Gerald Durrell (Penguin, £20) is out now. Visit expressbookshop.com or call Express Bookshop on 020 3176 3832. Free UK P&P on orders over £25